Shortcuts on this page
r m x toggle line displays
j k next/prev highlighted chunk
0 (zero) top of page
1 (one) first highlighted chunk
1import sys
4class VendorImporter:
5 """
6 A PEP 302 meta path importer for finding optionally-vendored
7 or otherwise naturally-installed packages from root_name.
8 """
10 def __init__(self, root_name, vendored_names=(), vendor_pkg=None):
11 self.root_name = root_name
12 self.vendored_names = set(vendored_names)
13 self.vendor_pkg = vendor_pkg or root_name.replace('extern', '_vendor')
15 @property
16 def search_path(self):
17 """
18 Search first the vendor package then as a natural package.
19 """
20 yield self.vendor_pkg + '.'
21 yield ''
23 def find_module(self, fullname, path=None):
24 """
25 Return self when fullname starts with root_name and the
26 target module is one vendored through this importer.
27 """
28 root, base, target = fullname.partition(self.root_name + '.')
29 if root:
30 return
31 if not any(map(target.startswith, self.vendored_names)):
32 return
33 return self
35 def load_module(self, fullname):
36 """
37 Iterate over the search path to locate and load fullname.
38 """
39 root, base, target = fullname.partition(self.root_name + '.')
40 for prefix in self.search_path:
41 try:
42 extant = prefix + target
43 __import__(extant)
44 mod = sys.modules[extant]
45 sys.modules[fullname] = mod
46 # mysterious hack:
47 # Remove the reference to the extant package/module
48 # on later Python versions to cause relative imports
49 # in the vendor package to resolve the same modules
50 # as those going through this importer.
51 if prefix and sys.version_info > (3, 3):
52 del sys.modules[extant]
53 return mod
54 except ImportError:
55 pass
56 else:
57 raise ImportError(
58 "The '{target}' package is required; "
59 "normally this is bundled with this package so if you get "
60 "this warning, consult the packager of your "
61 "distribution.".format(**locals())
62 )
64 def install(self):
65 """
66 Install this importer into sys.meta_path if not already present.
67 """
68 if self not in sys.meta_path:
69 sys.meta_path.append(self)
72names = 'packaging', 'pyparsing', 'six', 'appdirs'
73VendorImporter(__name__, names).install()